To install it you can do as any other plugin of WP.
NOTE: This will install to you only one plugin but with 2 different pages of configuration.
- Upload (you can do it to from the control panel) it to your /wp-content/plugins/ folder and activate it!
- The you need to configure Infinite Scroll (be carefull doesn't work with all the themes)
- Change something in WP-PageNavi if you want to
- Check your homepage it will be in the corner.
*To changes styles please open wp-pagescroll.css